Check out M4-M203 Low-poly 3D model on CGTrader for $85. High-quality mesh by Raider3DWeapons: 49000 polys, 44000 vertices. PBR, Textured, UV Mapped.
PNG (PNG, filesize: 1.17 GB), MAX (Autodesk 3ds Max, filesize: 12.4 MB), BLEND (Blender, filesize: 15.3 MB), FBX (Autodesk FBX, filesize: 6.44 MB)